1. Field of the Invention
The present invention relates to an optical scanning apparatus for scanning an original. The optical scanning apparatus is used, for example, to read an original in a copying machine or the like and to project the read image onto a photo-electric element (CCD element) or a conventional electrophotographic photosensitive medium.
2. Description of the Prior Art
Typical examples of such optical systems for scanning a stationary original are disclosed in Japanese Patent Application Publication No. 6,649/1964 (two mirrors are moved at the speed ratio of 2:1) and Japanese Patent Application Publication No. 10,912/1961 (lens is moved at a speed of 1/2 of the scanning speed).
The optical system disclosed in the former publication has such disadvantage that since the optical path is necessarily disposed under the scanning unit for scanning the original, almost all the space under the original table is occupied by the optical path forming part. An important disadvantage of the optical system disclosed in the latter is found in that a relatively narrow limitation is put on the location of mirror of the optical system. Moreover, the system becomes bulky because of the large size of the mirror which in turn limits the mechanical arrangement of the apparatus and causes a technical inconvenience.